Telephone system



H. A. LEWIS Feb. 1, 1938.

TELEIHONE SYSTEM 2 Sheets-Sheet 1 Filed Feb. 26, 1937 FIG. 2

INSULATION INVENTOR H A. LE W/S ATTORNEY Feb. 1, H A LEWIS 2,107,158

TELEPHONE SYSTEM Fi}.ed Feb. 26, 1957 2 Sheets-Sheet 2 /N 1/5 N TOR H/LLEW/S BV AT TQRNEV Patented Feb. 1, 1938 UNITED STATES GFFHQE TELEPHONE SYSTEM Application February 26, 1937, Serial No. 127,908

8 Claims.

This invention relates to telephone systems and particularly to improvements in the mechanism for establishing connections between subscribers lines at an exchange.

An object of the invention is to simplify and improve the mechanisms and circuits employed by the operators at an exchange for establishing telephone connections.

Heretofore systems have been provided for establishing connections between subscribers lines automatically or manually by the aid of cross-bar switch structures. Cross-bar switches are well known in the art in which connections between two lines are established by the operation of a selecting bar followed by the operation of a holding bar, the connection being established at the cross-point of said bars. Systems have also been provided in which the subscribers lines are associated with the holding bars and links are associated with the selecting bars. A connection between a calling subscribers line and 2. called subscribers line in this case is established by operating a holding bar to connect the calling line to one end of a preselected link and by operating another holding bar to connect the called subscribers line to the other end of this link.

The applicants invention has been disclosed in connection with a mechanism of the last mentioned type, in which each subscribers line and line lamp are associated with a holding bar and in which when a subscriber calls his line lamp is lighted at his associated holding bar whereupon the operator manually manipulates this holding bar to establish a connection between the calling subscribers line and one end of the preselected link. The operator whose telephone set may be associated with the link then inquires from the calling subscriber the number of the desired subscribers line. Upon the receipt of this number she operates the holding bar of the desired subscribers line and thereby connects the called subscribers line to the other end of the preselected link.

A feature of the applicants invention is an arrangement in a system of this type whereby when the subscribers replace the receivers on the switchhooks after a conversation, lamps are lighted in the engaged link and whereby the actuation of a key by the operator in the link flashes the line lamps of these subscribers lines to identify them with the engaged link. The connection may then be released by the manual restoring of the holding bars. The subscribers line lamp. may be located in a knob or plug that may be used for the manual operation of the associated holding bar.

The applicants invention has been illustrated in the accompanying drawings in'which Fig. l is a fragmentary side view in cross-section of a cross-bar switch structure suitable for use in connection with the applicants invention; and

Fig. 2 is a fragmentary plane view of this switch structure.

Fig. 3 is a circuit arrangement embodying the applicants invention with the cross-bar switch in accordance with Figs. 1 and 2 shown in diagrammatic form.

Referring now to the drawings, and particularly to Figs. 1 and 2, each end of a link is represented by three strips 5, 2 and 3 insulated from each other and the selecting bars associated therewith are shown in the form of flat bars 4, while each subscribers line is represented by a holding bar comprising three adjacent strips 5, 6 and I connected together at one end by an insulating piece 8 which in turn is connected to a plug 9 in a socket ill and in which is located the subscribers line lamp ll. An electrical connection may be made from this line lamp I I through one of the holding bar strips, for example the sleeve strip 5 to a contact 12 at the rear of the switch when the holding bar is in normal position. One terminal of the lamp Il may be connected to the sleeve strip 5 and the other connected to plug 9 which makes contact with the plate IS in front of the structure which in turn may be connected to ground. Another connection may also be made for the ring strip 1 at contact M to battery when the selecting bar is in normal position. The purpose of these connections at contacts I2 and M will become apparent as the description proceeds. The link strips l, 2 and 3 are provided with downwardly extending hooks M, 15 and I6 which are bent at their ends in a. common horizontal plane. The holding bars or subscribers line strips 5, 6 and l are provided with hooked members ll, I8 and [9 for engagement with the hooks l4, l5, (6, respectively at the cross-points of the selecting and holding bars in a manner as will hereinafter be described. It should be noted that a plurality of cross-bar switches such as described have been shown in the drawings with one switch on top of the other. There may be any number of such switches arranged in this manner in an exchange depending only on the number of lines terminating therein. There may, for example, be ten switches horizontally arranged one on top of the other and each switch may have ten subscribers lines holding bars. The link strips of the various switches may be strapped together in the manner illustrated in Fig. 3, that is two adjacent links in each switch are connected with the two corresponding ones in all the other switches arranged above or below them. The selecting bars 4 associated with the link strips are similarly connected together by vertical bars shown in diagrammatic form in Fig. 3, and indicated by the numeral 20 for the first link which are operated by solenoids 2i and 22 to rotate the connected selecting bars 4 or tilt them for the purpose of selecting as will hereinafter be described.

This mechanism operates as follows: If, for example, the magnet 23 associated with the last link and illustrated in dotted lines in Fig. 1 has been operated, the bar 24, also illustrated in dotted lines in this figure, causes the selecting bars 25 to 28 to be turned to the position shown and then plug 9 at 30 is pulled towards the left by the operator, the projections I'I, I8 and I9 at 3i will beraised due to the humps on these projections and then lowered to a position where they will contact respectively with the hooks I4, i5 and I6 on the link strips at 33. 'A connection will therefore be established from a calling subscribers line connected to the holding bar associated with the plug at 30 to the link strips at 34. These link strips may be named calling link strips. In a similar manner, a called subscribers line may be connected through a holding bar to the companion link strips that may be named called link strips. It should be understood that as soon as the calling link strips have been connected the bars 4 of this link will be restored to normal and the selecting bar 4 of the companion called link strips will be automatically tilted so that the called line strips will be connected, when the called line plug is pulled out, with the called link strips of this link. It should be observed that the selecting bars 25, 26 and 28 will not disturb the projections I1, It and I9 on other holding bars, as for example, in the case of the bars at 35 which have already been operated, there is room enough for the selecting bar 25 to move into the tilted position shown due to the bent portion of the projections I'I, I8 and I9 of this bar. Similarly in case of the selecting bar 26, the projections on the bar at 3B, which has not been operated, will not be disturbed due to similar bent portions on the projections I'l, I8 and I9.

Referring now to the operation of the circuit as shown in Fig. 3, it will be noted that the link circuit shown at I00 terminates in a calling end in the tip, ring andsleeve conductors at IOI multipled to the corresponding calling link tip, ring and sleeve strips of the different layers of switches, the upper and lower of which have been shown in'diagrammatic form. This link circuit also terminates in the called end in tip,

ring and sleeve conductors at I02 multipled to the corresponding called link tip, ring and sleeve strips of the different layers of switches; A connection from acalling subscribers line such as I03 may therefore be extended through contacts at the cross connecting point I04 through the calling end of the link circuit at I00 over the called end of the link through, for example, a

cross connecting point I05 to a called subscribers line I06. The link I00 is shown as the first link in the system. A second link arrangement has been shown at I01. Normally, the first link 'circuit is preselected by the normal operation of the magnet 2! which has operated to cause the rod 20 to tilt the various selecting rods 4 indicated in this figure merely by lines. These tilted bars 4, therefore, make it possible to connect a calling line with the calling end of the link I 00. The circuit for magnet 2I may be traced from battery through an armature and back contact of relay IIO, an upper armature and back contact of relay I I I, through the Winding of magnet 2! to ground.

If now the subscriber of line I03 removes his receiver from the switchhook the lamp II2 of this line will be lighted over a circuit from battery, contacts l4 associated with the ring strip over the ring conductor through the loop at the calling subscribers station over his line I 03, back over the tip conductor, through contacts I2 over the sleeve strip through the lamp H2 to ground. This indicates to the operator in attendance that this subscriber desires to make a call. She consequently pulls out the plug 9 of the calling subscribers line bar and thereby establishes a connection between the tip, ring and sleeve strips of this line and the corresponding tip, ring and sleeve strips of the calling end of link I 00 at cross connecting point 504. is established in the manner described in connection with Figs. 1 and 2. In pulling out this plug the lamp H2 is extinguished as the connections through contacts I2 and I4 are opened. Relay III is now operated from battery and ground through its windings, tip and ring conin operating closes a circuit for the lighting of lamp H3 from battery through the lower armature and front contact of relay III, contacts of relays H4, H5 and H0, lamp II3 to ground. The lighting of this lamp indicates to the operator which link the calling subscribers line is connected to. She consequently operates the talking key I I6, and thereby connects her telephone set II! to the link I00, answers the calling subscriber and receives the desired subscribers number. When relay III operated the circuit hereinbefore traced for magnet 2| is opened at the upper armature and back contact of this relay and magnet 2! in releasing closes a circuit for the operation of the magnet 22 from. battery, contacts of relays H5 and H4, Winding of mag net 22, contacts of magnet 2i to ground. This magnet now prepares the selecting bars 4 of the called end of the link I00 for a connection to a called subscribers line. understood that the propersubscriber number may be marked on the front of the plate I3 or on the individual plugs for each subscribers line. Consequently, the operator may now search for the called subscribers number on this plate and when found pull out the corresponding plug 9; in this case the one leading to the subscriber of line I06 may be chosen. This causes a connection to be established at the cross connecting point I05 between the called end of the link over the tip, ring and sleeve conductors and the called subscribers line I06. The connection for the sleeve conductors causes the operation of relay H5 from battery, contacts of relay II 4, winding of relay H5, the sleeve conductor, point I05'and lamp I22 to ground. This lamp I22 does not receive sufficient current to light it at this time due to the resistance of the winding of relay H5.

It should ofcourse be r This connection at I04 battery, contacts of relays H4 and H5, lamp I24 to ground. Relay H5 in operating also opens the circuit for magnet 22 at its outer righthand armature and back contact causing this magnet to release and restore bars 4 to normal. This magnet closes at its armature and back contact a circuit to ground for the preselection of the magnet for the calling end of the next link, that is, in this case magnet 23 as noted in Fig. 3, so that this magnet will operate to prepare the next link for a call. The operator in observing the lighted lamp I24 knows that the called subscribers line has been connected to the link and will therefore ring the called subscriber by operating the ringing key I26 in the usual manner.

When the called subscriber. at I06 answers this call and the operator restores the ringing key I26, relay H4 operates from battery and ground through its windings, contacts of the ringing key I20, the connection through the tip and ring conductors over the called end of the link through the point I05 and the loop of the called subscribers line I00. Relay H4 in operating opens the circuit for relay H5 which releases and extinguishes lamp I24. A connection is now established from the calling subscribers line I03 to the called subscribers line I through link I00, and talking batteries for these subscribers are supplied through windings of relays III and H4 and a talking connection through condensers I2! and I28.

After conversation is finished and, for example, the calling subscriber replaces his receiver on the switchhook the relay III is released. This relay closes a circuit for the operation of relay III]. This circuit may be traced from battery through contacts of relay III, winding of relay H0, the calling end of the link, point I04, lamp H2 to ground. Lamp H2 does not receive sufficient current to light due to the resistance of the winding of relay H0. Relay H0 in operating closes an obvious circuit for the lighting of lamp I I3. This indicates to the operator that the calling subscriber has hung up his receiver.

When the called subscriber hangs up his receiver relay I I4 is released. This causes the operation of relay H5, and the lighting of lamp I24 over circuits hereinbefore traced. As both lamps I I3 and I24 are now lighted, the operator will know that the connection through this link has been relinquished by both subscribers. It is now only necessary to restore the plugs 9 of the calling and called subscribers lines in the switch in order to release these lines at the points I04 and I05 from the link and restore the link to common use. To identify the plug of the calling subscribers line plug for this purpose the key I30 is operated repeatedly. This applies battery to the sleeve for lamp H2 and causes this lamp toflash which identifies lamp IE2 as that of the calling subscriber associated with link I00 and the operator may then restore the corresponding plug 9 to release the connection to this subscriber. This causes the release of relay I I0 and the extinguishing of lamps I I3. The operator will then operate key I30 towards the right to similarly flash the lamp I22 oi the plug 9 of the called subscribers line. When this identification is made she restores the corresponding plug 9 to normal and opens the connection at I05, thereby restoring the relay H5 and extinguishing the lamp I24. The link I00 may then be used for other calls.

What is claimed is:

1. In a system comprising cross-bar switches, subscribers lines, holding bars, selecting bars,

links, means for establishing a connection between a calling subscribers line and a called subscribers line over a. link through a switch responsive to the automatic selection of two selecting bars and the manual operation of two holding bars, and manually operative means for identifying the two manually operated holding bars for the restoration thereof to normal to release said established connection.

2. In a system comprising cross-bar switches, subscribers lines, holding bars, selecting bars, links, means for establishing a connection between a calling subscribers line and a called subscribers line over a link through a switch responsive to the automatic selection of two selecting bars and the manual operation of two holding bars, an operators position, means responsive to the calling subscriber and called subscriber re placing their receivers on the. switchhooks for identifying the engaged link, and manually operated means for identifying the two manually operated holding bars with said engaged link for the manual restoring of said bars to normal to release said established connection.

3. In a cross-bar switching system, subscribers lines, selecting bars, holding bars, links, means for establishing a connection between a calling subscribers line and a called subscribers line over a link through a cross-bar switch in said system responsive to the automatic operation of two selecting bars and the manual operation of two holding bars, a signal associated with each subscribers line, a key associated with each link, means responsive to the operation of the key of an engaged link for actuating the signals of the connected subscribers lines to identify said lines with said engaged link, and means responsive to the manual restoring of said holding bars for releasing the established connection between the calling and the called subscribers lines.

4. In a cross-bar switching system, subscribers lines, selecting bars, holding bars, links, means for establishing a connection between a calling subscribers line and a called subscribers line over a link through a switch in said system responsive to the automatic operation of two selecting bars and the manual operation of two holding bars, a signal associated with each line, signals associated with each link, a key associated with each link, means for actuating the signals associated with the engaged link in response to the calling and called subscribers replacing their receivers on the switchhooks, means responsive to the actuation of the key associated with the engaged link for actuating the signals of said subscribers lines for the identification of said subscribers lines with said engaged link and means responsive to the restoring of the actuated holding bars for releasing the established connection.

5. In a cross-bar switching system, subscribers lines, selecting bars, holding bars, links, each link having a calling branch and a called branch, means for establishing connections between a calling subscribers line and the calling branch of a link and between a called line and the called branch of said link in response to the automatic operation of two selecting bars individual to said link and the manual operation of two holding bars individual to the calling subscribers line and the called subscribers line respectively, a signal associated with each subscribers line, a signal associated with each branch of a link, means for actuating the signals of the engaged link in response to said subscribers replacing their receivers on the switchhooks, means for actuating said subscribers line signals to identify them with the engaged link, and means responsive to the manual restoring of the operated holding bars for releasing said connection and disabling the actuated signals.

6. In a telephone system, a cross-bar switch comprising manually operable holding bars and automatically operable selecting bars, links each controlled by a pair of automatically operated selecting bars, circuit means for preselecting a pair of selecting bars of a link, means responsive to the manual operation of two holding bars for establishing a connection between a calling subscribers line and a called subscribers line over said preselected link through said switch, and manually operative means for identifying the pair of manually operated holding bars with the engaged link for the manual restoring of said bars to release the connection.

'7. In a telephone system, a cross-bar switch comprising manually operable holding bars and automatically operable selecting bars, links each controlled by a pair of automatically operated selecting bars, circuit means for preselecting a pair of selecting bars of a link, means responsive to the operation of the two holding bars for establishing a connection between a calling subscribers'line and a called subscribers line over said preselected link through said switch, manually operative means for identifying the pair of manually operated holding bars with the engaged link, and means responsive to the manual restoring of said operated holding bars for releasing the connection.

8. In a system comprising cross-bar switches, subscribers lines, holding bars, selecting bars, links, means for establishing a connection between a calling subscribers line and a called subscribers line over a link to a switch responsive to the automatic selection of two selecting bars and the manual operation of two holding bars, a signal associated with each holding bar, and means for flashing the signals associated with the two manually operated bars for identifying said bars for restoring them to normal to release said established connection.

HERBERT A. LEWIS. 

